If a sdist and a pure py package exist, try to build sdist first

[Marco-Sulla]

What's the problem this feature will solve?

Currently, if a module have a pure py wheel published on Pypi and your architecture is not present in the prebuilt packages, pip installs the pure python wheel, even if on Pypi is present an sdist package.

Describe the solution you'd like

I suggest to make pip try to build first from sdist, and if it fails, install the pure py package if present.

Alternative Solutions

Current workaround is to make the C extension optional and remove the pure python package.

This is problematic, since it requires an additional effort for module testers. Furthermore, if the C extension fails to compile, the produced wheel is not named as a pure python one.

Additional context

PS: I'm a maintainer of a C extension. I had to change my code and use the workaround.

Code of Conduct

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